Device for equalizing strains on hoisting ropes



Dec. 19, 1933. J. E. EVANS DEVICE FOR EQUALIZING STRAINS ON HOISTINGROPES Filed Dec. 3. 1931 2 Sheets-Sheet l J. E. EVANS Dec. 19, 1933.

DEVICE FOR EQUALIZING STRAINS ON HOISTING ROPES Filed Dec. 3. 1931 2Sheets-Sheet 2 Patented Dec. 19, 1933 DEVICE FOR EQUALIZING STRAINS ON.HOISTING ROPES Joseph E. Evans, Bedford, Ind., assignor to EvansElevator Equalizer Company, Bedford, Ind., a corporation of IndianaApplication December 3, 1931. 'Serial No. 578,625

16 Claims. (01. 18'71) My invention relates to a device for equalizingstrains which, in the particular embodiment hereinafter described, wasmore particularly designed for use in connection with hoisting cablesemployed for raising and lowering elevator cars carrying passengers orfreight from one floor to another of buildings, especially tallbuildings of the sky-scraper type developed in recent years. In suchinstallations it is commen practice to employ a group of wire cablesconnected at one end to the car and 'at the other end to acounterweight, and tracking in peripheral grooves in a suspension drum,or pcwer-driven hoisting drum, at the top of the elevator shaft. As isalready well understood, a tendency to unequal travel .of the cablesover the hoisting drum is apt to arise from unavoidable inequality inthe depth of the grooves of the pulley, or differences in the size ofthe cables,

or the amount of stretch which they exhibit from various causes, andmeans for permitting such variation in travel while maintaining an equaltension .on all the cables is highly important. It is the object of myinvention to 5 provide an improved strain-equalizer for such use of thetype employing floating pulleys severally connected to the cables and anequalizing cable engaging in alternation such fioating pulleys .and aset of lower pulleys secured to the car, which shall have certain noveland desirable features of construction in the arrangement of the twosets of pulleys, the construction of a block member providing bearingsfor the lower pulleys and an associated retaining plate, a 5 pulleyblock and connected safety bolt which provides also a bearing abutmentfor certain biasing springs employed in the device, and in other detailsin the construction and arrangement of the parts of the device whichwill be apparent from the description hereinafter given.

Among the objects of my invention may be mentioned the biasing springsbefore referred to, operating in a novel manner to yieldingly stress thehoisting cables in such a way that they will tend to return to apre-adjusted uniform normal position with reference'to their attachmentto the car and counterweight. With the ends indicated in view I havedevised and invented the equalizing suspension device hereinafterdescribed in.- detail, the essential elements of my invention being moreparticularly pointed out in the appended claims. v

In the drawings, Figure 1 is a side view of fragments of an elevator carand a counterweight connected to each other by means of hoistingcablesrunning over a hoisting drum and secured to the car and counterweight bymeans of my novel equalizing devices;

Fig. 2 is a front view of the form of equalizer secured to thecounterweight;

Fig. 3 is a side view of the same; v

Fig. 4 is a horizontal section of the device just above the floatingpulleys, the plane of the section being indicated by the dotted line 4-4of Fig. 2; 6

Fig. 5 is a horizontal section on the line 55 of Fig. 2; v

Fig. 6 is a fragmentary section in a plane indicated by the dotted line6--6 of Fig. 5;

Fig. 7 is a fragmentary section of the same parts as indicated by thedotted line 7-7 of Fig. 6, showing the plane of the section;

Fig. 8 is a vertical section extending transversely of the supportingbeams of the car (as counterweight), illustrating a modified form ofbearing casting for rotatably supporting the equalizing pulleys securedto the car; and

Fig. 9 is a second modified form of bearing block which may be employedfor the same purpose.

Like-reference characters indicate like parts in all the figures of thedrawings.

For reasons which will later be explained I connect the group ofhoisting cables connecting the car and counterweight at the end only (asthe counterweight end) by means of an equalizing device provided withbiasing springs, while at the opposite end they are connected by meansof a device which is, or may be, substantially the same, excepting thatit is not provided with biasing springs. In the constructionillustrated, the car A, a fragment of which is shown, is connected byone of my novel equalizingdevices B with the group of hoisting cables 0which run in grooves in the hoisting drum D and idler drum E in a mannerwell-known in elevator installations, the other end of the cables beingconnected to the counterweight F by the equalizer G, which is of thesame construction as the equalizer B, excepting for the additionalprovision of biasing springs, as before mentioned, and as will later bedescribed in detail.

Describing first the construction of the equalizer G, it will beunderstood that the frame of the counterweight (or of the car, in casethe arrangement should be reversed) includes ordinarily, and as shown, apair of parallel channeliron beams 1-1 which are spaced apart a properdistance to provide for the reception .between them of a bearing-blockmember 2 which n A o u in the form of my invention illustrated in Figs.1 to 3 is a metal casting flanged at the top and formed with bolt holesarranged to receive clamping bolts 3 which engage also orificedcross-bars 4 below the beams l and serve. to secure the bearing block tothe car.

As best shown in Figs. 6 and 7 the blocks 2 are formed with verticalslots whichextend through them from top to bottom the overlapping zigzagorder shown in Fig. 5, and which are of proper size to receive the loweror equalizing pulleys 6, five in number in the present case. Thesepulleys are pivotally mounted upon bearing pins 7 which extend throughthem and project on both sides into opposite semi-cylindrical seatsformed at the top of vertical recesses 8 which extend in oppositedirections from the faces of the slots 5. Below the bearing pins 7 ofthe pulleys 6, in the recesses 8 mentioned, are arranged filler blocksBZ'preferably of wood by means of which the pins are firmly secured, inplace and prevented from rotating. To the bottom of the casting l isbolted a retaining plate 9 which servesto clamp the filler blocks inposition and prevents disengagement of the parts when assembled.

It may here be explained that the hoisting cables C, six in number inthe present instance, are individually connected to the members of a setof upper, floating pulleys 10 which are engaged in loops of anequalizing cable 11 anchored at its ends by rope socket blocks 12 to theassociated retaining plate and bearing block,

. and consequently to the counterweight (or car) frame, as shown inFigs. 2 and 3.

Describing next the parts associated with the hoisting cables andfloating pulleys 10, each cable C is secured to a threaded socket block13 which is connected by a right-and-left threaded adjusting bolt 14with the threaded shank of a pulley block 15 formed with parallel sideportions 1'7 between which the'associated pulley is pivotally mounted,lock nuts 16 being provided to secure the parts together in adjustedrelation.

Preferably, and as shown, the side portions 17 of each pulley block 15extend downwardly in the form of a pair of elongated ears between thelower ends of which is pivotally mounted the upper eye portion of asafety bolt lawhich below extends loosely through orificesin the block 2and retaining plate 9. The opening between the portions 17 of the pulleyblock provides space for the threading of the equalizing cable 11through the block after the cable has been cut to proper length andequipped with sockets, the pulley being removed for this purpose.However, if desired .the lower end of the portions 17 may be connected,sufficient space for threading the equalizing cable being otherwiseprovided. At its lower threaded end each bolt carries nuts 19 whichserve to adjustably confine between it and the retaining plate above ita coiled compression biasing spring 20 which under its intended normaladjustment is not under any tension, but just contacts the retainingplate and the upper nut. The nuts 19 at the lower end of the safetybolts form heads for the latter whichin case the equalizing cable shouldbreak will bring up against the bearing block 2, the springs 20 in suchcase acting as buffer members.

While I regard the jointed flexible connection provided by the ears 17of the bearing block 15 and the eye of the bolt 18 as desirable, it willbe understood that a rigid connection of the bearing member and bolt maybe provided if preferred. Also, it will be understood that means forpreventing rotation of the connected parts while permitting a verticalsliding movement of the bolts 18 with relation to parts stationarilysecured to the counterweight, or car, as by a ieathered connection, orits equivalent, may be provided if desired.

The floating pulleys 10, like the lower pulleys 6, are arranged in frontand rear rows in overlapping inclined relation, in such manner that theequalizing cable 11 will track vertically from its point of anchorageunderneath the right side of the right member of the group of upperpulleys and adjacent the right end of the group of lower pulleys, asviewed in Fig. i, to the groove of said right hand upper pulley, andthen in succession will track in vertical stretches between the lowerandupper pulleys in a zigzag path to its point of anchorage adjacent theleft end of the group of lower pulleys and directly underneath the leftside of the left upper pulley. The arrangement is such that the loops ofthe equalizing cable engaged bythe upper pulleys will extend alternatelyforwardly of and rearwardly of the longitudinal center line of the groupof such upper pulleys in staggered and oppositely inclined overlappingrelation.

As above explained the lower pulleys, which are. likewise staggered andoppositely inclined from. the longitudinal center line of the group, butat a different angle of inclination, are so arranged that the reaches ofthe equalizing cable between the upper and lower pulleys trackvertically, and from this different inclination of angles and thestaggered overlapping relationship of the parts it results that the loopof the cable around each upper pulley tracks in one reach into a pulleyon one side (front or rear) of the device and in the other reach into apulley on'theopposite side of the device-01 to an anchorage at theends-and from each lower pulley the equalizing cable likewise tracksinto an upper pulley on one side and another upper pulley on theopposite side of the device.

Inasmuch as the space between the channel- .ii'on beam members whichconstitute the crosshead of the car frame is in some makes and. stylesof elevators quite narrow, it is obvious that the inclined and staggeredrelationship of the pulleys is of great utility in enabling the lowerpulleys, to be compactly arranged and capable of installation in thespace between the pulleys of greater diameter to be employed in a givenspace than by any other arrangement known to me. The pulleys shown inthe rangement illustrated are approximately of the same size and ifdesired pulleys of precisely the same diameter may be used by slightmodification of proportions, while retaining the same arrangement. It isobvious that where space permits a widening of the casting pulleys ofgreater iameter may beused, and also that the angles of inclination, aswell as the diameter of the biasing springs are unnecessary.

pulleys, may be changed as necessary 01' desired to vary the spacing ofthe rope centers.

The equalizing device used at the car end of the. hoisting cables(marked B as a whole in Fig. 1) differs from the equalizer abovedescribed only in that the springs 20 are omitted, and that due to theomission of the springs the bolts 18 are somewhat shortened.

It will be understood that in the usual functioning of the device,inequalities in size of parts or degree of stretch in the hoistingcables will be taken up by a shifting of relative vertical position ofthe upper pulleys as the cables run in one direction over the suspensiondrum,

and that the causes producing unequal travel of the hoisting cables willact in the reverse direction to restore the pulleys to their originalposition as the car moves in the opposite direction and returns to itsfirst position. So far as these conditions are concerned, therefore, theIt has been found, however, that in some cases one or more of thehoisting cables may tend to creep in one direction or the other in itsgroove in the suspension drum, probably because of unequal twist in thecables, or slippage from other reasons not fully understood. In anycase, whether with or without creeping or slippage, any difference inthe horizontal position of the pulleys of that one of the equalizerprovided with biasing springs acts to put the spring of any oneor moreof the pulleys standing higher than its normal position of equalhorizontal adjustment under a compressive strain acting on theparticular hoisting rope in the same direction as the stress of gravityexerted through the equalizing cable on the pulley connected to suchrope, and the spring thus takes up a part of the weight of the car andcorrespondingly relieves the weight on the remaining cables.

The total weight of the car is accordingly in part taken up severally bysuch springs as are under compression and these portions communicateddirectly to-the cables respectively stressed by the springs while theremaining weight is sustained in equal parts by the floating pulley anddistributed equally among the cables. The expansive stress of anyparticular spring under compression manifestly tends to restore theconnected pulley to its normal position in which the spring isuncompressed, although to an extent deter-mined by the strength of thesprings, their effect is to prevent perfect equalization of the strainon the hoisting cables. I therefore employ them upon one end of thecables only, --preferably the counterweight end,-since in the travel ofthe car and counterweight from one extreme posiheight above the lowerpulleys.

The arrangement of the channel iron frame members of the car (orcounterweight) through which my equalizing device is secured to the carvary in elevator cars of different sizes and makes, and it is desirableto provide means for adapt- The perfecting my device to cars differingin construction. In Fig. 8 I have shown the position. and arrangement ofa bearing block for the lower pulleys, marked 30, which may be installedbetween the channel members 1 of thecar frame, and secured in positionby bolts 31 equipped with nuts engaging the bearing block structure andcross-bars 5-5 above and below the members 1.

In Fig. 9 I have shown a differently formed bearing block 32, formedwith flanges 33 on its lower side extending beneath the channel ironframe members 1, and secured to such members by clamping bolts 34engaging the cross-bar 5 above said frame members.

I claim: v I

l. A suspension device for connecting an elevator car to a group ofhoistingropes including a plurality of floating pulleys severallyconnected with the hoisting ropes, a plurality of other lower pulleysone less in number than said floating pulleys pivoted to the car, and anequalizing cable anchored at both ends to the car and engaging saidfloating pulleys and lower pulleys in alternation, said floating pulleysbeing arranged in front and rear rows disposed in staggered relation andsaid lower pulleys being also disposed in front and rows in staggeredrelation, the arrangement being further such that said equalizing cablewill track between said pulleys in vertical reaches from one point ofanchorage adjacent one end of said group of lower pulleys to its otherpoint of anchorage adjacent the opp0- site end of such group of lowerpulleys in a generally'zigzag path in loops extending in alternate orderbetween said front and rear rows of pulleys.

2. A suspension device according to claim 1 "n wl1ich the pulleys of onerowv of one set of ulleys are inclined from the longitudinal center neof the device oppositely with respect to the ulleys of the other row.

3. A suspension device according to claim 1 in which the pulleys of onerow of each set of pulleys are inclined from the longitudinal centerline of the device oppositely with respect to the pulleys of the otherrow of the particular set, and in which the angle of inclination of thepulleys of one'set differs from that of the other set.

'4. A suspension device according to claim 1 in which the outer reach ofeach loop of the equalizing cable engaging a lower pulley tracks into afloatin pulley on the same side of the device and the inner reach tracksinto a floating pulley on the other side. I

5. A suspension device according to claim 1 in which the outer reach ofeach loop of the equalizing cable engaging a lower pulley tracks into afloating pulley on the same side of the device and the inner reachtracks into a floating pulley on the other side, and in which the innerreaches of theequalizing cable lie in alternate order upon oppositesides of the longitudinal center line of the device.

6. A suspension device for connecting an elevator car to a group ofhoisting ropes including a plurality of floating pulley blocksindividually connected to said ropes and floating pulleys in saidblocks, an orificed bearing block secured to the car, other lowerpulleys pivotally mounted in said bearing block, an equalizing cableanchored to the car and engaging said floating and lower. pulleys inalternation, and headed safety bolts severally secured to said pulleyblock and slidably passing through orifices in said bearings block.

7. A suspension device for connecting an elevator car to a group ofhoisting ropes including a plurality of floating pulley blocksindividually connected to said ropes and floating pulleys in saidblocks, an orificed bearing block secured to the car, other lowerpulleys'pivotally mounted in said bearing block, an equalizing cableanchored to the car and engaging said floating and lower pulleys inalternation, headed safety bolts severally secured to said pulley blockand slidably passing through orifices in said bearing block, and buffermember between said bolts and bearing block.

8. A suspension device for connecting an elevator car to a group ofhoisting ropes including a plurality of floating pulley blocksindividually connected to said ropes and floating pulleys in saidblocks, an orificed bearing block secured to the car, other lowerpulleys pivotally mounted in said bearing block, an equalizing cableanchored to the car and engaging said floating and lower pulleys inalternation, headed safety bolts severally secured to said pulley blockand slidably passing through orifices in said bearing block, andcompression springs arranged severally on said bolts between the headsthereof and said bearing block.

9. A suspension device for connecting an elevator car to a group ofhoisting ropes including a plurality of floating pulley blocksindividually connected to said ropes and floating pulleys in saidblocks, an orificedbearing block secured to the car, other lower pulleyspivotally mounted in said bearing block, an equalizing cable anchored tothe car and engaging said floating and lower pulleys in alternation, andsafety bolts severally pivoted to the lower ends of said pulley blocksand headed at their lower ends, said bolts being arranged to slidablypass through orifices in said bearing block.

10. A suspension device for connecting an elevator car to a group ofhoisting r0 es including a plurality of floating pulley blocksindividually connected to said ropes and floating pulleys in saidblocks, an orificed bearing block secured to the car, other lowerpulleys pivotally mounted in said bearing block, an equalizing cableanchored to the car and engaging said floating and lower pulleys inalternation, headed safety bolts severally secured to said pulley blockand slidably passing through orifices in said bearing block, andcompression springs interposed between the heads of said bolts and saidbearing block, said springs being in normal position of the parts underno stress.

' 11'. The combination, in an elevator system including a car and acounterweight, of a plurality of hoisting ropes, a hoisting drum engagedby said ropes, an equalizing device connecting said ropes at one end tosaid car, and a second equalizing device connecting said ropes at theother end to said counterweight, one only of said equalizing devicesincluding biasing means tending to yieldingly maintain the hoistingropes in a certain position of longitudinal relationship to each other.

12. The combination, in an elevator system including a car and acounterweight, of a plurality of hoisting ropes, a hoisting drum engagedby said ropes, an equaiizing device connecting said ropes at one end tosaid car, and a second equalizing device connecting said ropes at theother end to said counterweight, the equalizing device connected to saidcounterweight only including biasing means tending to yieldinglymaintain the hoisting ropes in a certain position of longitudinalrelationship to each other.

13. The combination, in an elevator system including a car and acounterweight, of a plurality of hoisting ropes, a hoisting drum engagedby said ropes, an, equalizing device connecting ropes at one end to saidcar, and a second equalizing device connecting said ropes at the otherend to said counterweight, the equalizing device connected to saidcounterweight including springs severally connected to the ropes, saidsprings being in normal position of the ropes under .no stress and uponrelative longitudinal shifting of the position of the ropes beingindividually tensioned in opposition to a movement shortening theparticular rope.

14. In an equalizing device for connecting hoisting ropes to an elevatorcar, said device including upper and lower sets of pulleys connected byequalizing rigging, means for pivotally securing the pull ys of saidlower set to the car including a cast metal bearing block arranged'to besecured between car frame members, said block being formed with two rowsof inclined staggered vertical orifices arranged to receive the pulleys.I

15. In an equalizing device for connecting hoisting ropes to an elevatorcar, said device including upper and lower sets of pulleys connected byequalizing rigging, means for pivotally securing the pulleys of saidlower set to the car including a cast metal bearing block arranged tobesecured between car frame members, said block being formed with two rowsof inclined staggered vertical orifices arranged to receive the pulleys,and the side walls of said orifices being formed with vertical groovesextending upwardly from the bottom of the casting to the axis of thepulley, and pivots fixed in said blocks at the top of said grooves.

16. An equalizing device having the structure recited in claim 15 inwhich filler blocks are arranged in the vertical grooves mentioned insaid claim and a retaining plate is secured to the bearing block belowsaid filler blocks.

JOSEPH E. EVANS.

